Thermoplastic material such as adhesive, supplied in an elongated, flexible rod, for instance, as disclosed in U.S. Pat. No. 2,874,084, or other solid, granular or particulate form is desirably supplied on demand to a point of application and as reduced to liquid form. Portable thermoplastic cement dispensers wherein manual feeding is employed is disclosed, for example, in U.S. Pat. No. 3,204,828 issued Sept. 7, 1965, in the name of H. C. Paulsen, and in U.S. Pat. No. 3,298,572 issued Jan. 17, 1967, in the name of A. E. Newton. A similar tool embodying mechanized means for feeding the thermoplastic into a melt chamber is disclosed in U.S. Pat. No. 3,743,142 issued in the names of the present joint inventors. Additionally, in endeavors to provide improved thermoplastic melting and applying systems for use in hand held extruders, illustrative disclosures have been made in U.S. Pat. Nos. 3,337,093 and 3,776,426, both issued to Mr. Newton.
The disclosure of the last patent referred to above aims at increasing the melting capacity for a given size melt chamber of a through-feed adhesive extruder. As therein shown the extruder comprises the configuration of the chamber, a milled collecting manifold, and interconnecting by-passes in the form of transversely milled channels which connect with grooved-out portions of the chamber for relieving the chamber of the thermoplastic as it is progressively liquefied. While melt bodies of the type just identified have proven commercially advantageous in both industrial and consumer hot melt cementing devices, it is desirable even further to enhance melting capacity while providing a melt body of simpler construction and lower unit cost.